In a graphics processing system, it is important to manage and control multiple command threads relating to texture applications. In a typical graphics processing system, the processing elements, such as vertices and/or pixels, are processed through multiple steps providing for the application of textures and other processing instructions, such as done through one or more arithmetic logic units (ALU). To improve the operating efficiency of a graphics processing system, the control of the flow of the multiple command threads is preferred.
FIG. 1 illustrates a prior art sequencing system 100. The system 100 includes a first arbiter 102, a second arbiter 102 and a third arbiter 103 and multiple buffers 104, 106, 108 and 110. In a typical embodiment, the buffers are first in and first out (FIFO) buffers. Each of the buffers 104-110 include multiple command threads, such as 112, 114, 116, 118 stored therein. Moreover, the system 100 is divided into resource divisions, such as an ALU resource division 120 and a texture fetch resource division 122. In the ALU resource division 120, the command thread 118 may be received from an input command 124 as selected by the arbiter 101. The command thread 118 may then be withdrawn from the reservation stations 104 and 108 for the purpose of being provided to an ALU (not shown) and the command threads within the texture fetch resource division 122 may be withdrawn from the reservation stations 106 and 110 to be provided to a texture fetch processors (not shown).
In the prior art embodiments of FIG. 1, the first buffer 104 receives an input command 124 and outputs a completed command thread 126 to the second arbiter 102. In one embodiment, the command thread may include an indicator, such as a flag, indicating when the access to the ALU resources has been completed for the associated command. The arbiter 102 receives the input command 124 and thereupon provides, in due course, the command thread to either an appropriate texture fetch buffer 110 or an ALU buffer 108. Thereupon, the steps are repeated where an output thread command 128 is provided to another ALU (not shown) or texture fetch processor (not shown) and returned to the buffer 108 or 110. The buffer 110 also produces the output 132 which is a command thread. The output 132 may be provided to another arbiter 103 to be provided further along the graphics processing pipeline.
The embodiment of FIG. 1 illustrates an inflexible system having specifically delineated ALU resource buffers and texture fetch resource buffers such that command threads must be sequentially provided between the various buffers 104, 106, 108 and 110. Furthermore, the system 100 of FIG. 1 does not support an unlimited number of dependent fetches based on the structure of the buffer 104-110 structure and connectivity between each other and with respect to available ALU resources and texture fetch resources.
As such, there is a need for a sequencing system for providing for the processing of multi-command threads that supports an unlimited number of dependent texture fetches.